Method and apparatus for transmitting downlink control information in wireless communication system

ABSTRACT

The disclosure relates to a communication method and system for converging a 5 th -Generation (5G) communication system for supporting higher data rates beyond a 4 th -Generation (4G) system with a technology for Internet of Things (IoT). A method of a user equipment is provided. The method includes identifying a first bandwidth part for a cell and a second bandwidth part for the cell through a radio resource control signaling, wherein each of the first bandwidth part and the second bandwidth part is defined with a corresponding subcarrier spacing and frequency domain location; identifying a first control resource set on the first bandwidth part and a second control resource set on the second bandwidth part through the radio resource control signaling; and acquiring second downlink control information for the second bandwidth part based on the first control resource set on the first bandwidth part being activated.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation Application of U.S. patentapplication Ser. No. 16/037,524, filed on Jul. 17, 2018, and claimspriority under 35 U.S.C. § 119(a) to Korean Patent Application SerialNumber 10-2017-0090220, filed on Jul. 17, 2017 in the KoreanIntellectual Property Office, the entire disclosure of which isincorporated herein by reference.

BACKGROUND 1. Field

The disclosure relates, generally, to a wireless communication system,and more particularly, to a method and apparatus for transmittingdownlink control information in a next generation mobile communicationsystem.

2. Description of the Related Art

Efforts have been made to develop an improved 5G or pre-5G communicationsystem, which is also called a “beyond 4G network” or a “post LTEsystem”. The 5G communication system is considered to be implemented inhigher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplishhigher data rates. To decrease propagation loss of the radio waves andincrease the transmission distance, the beamforming, massivemultiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO),array antenna, an analog beam forming, large scale antenna techniqueshave been contemplated for use with the 5G communication systems. Inaddition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation and the like. In the 5G system, hybridfrequency-shift keying (FSK) and quadrature amplitude modulation (QAM)(FQAM) and sliding window superposition coding (SWSC) as an advancedcoding modulation (ACM), and filter bank multi carrier (FBMC),non-orthogonal multiple access (NOMA), and sparse code multiple access(SCMA) as an advanced access technology have been contemplated.

The Internet is now evolving to the Internet of things (IoT) wheredistributed entities, such as things, exchange and process informationwithout human intervention. The Internet of everything (IoE), which is acombination of the IoT technology and the big data processing technologythrough connection with a cloud server, has emerged. As technologyelements, such as sensing technology, wired/wireless communication andnetwork infrastructure, service interface technology, and securitytechnology have been demanded for IoT implementation, a sensor network,a machine-to-machine (M2M) communication, machine type communication(MTC), and so forth have been recently researched. Such an IoTenvironment may provide intelligent Internet technology services thatcreate a new value to human life by collecting and analyzing datagenerated among connected things. IoT may be applied to a variety offields including smart home, smart building, smart city, smart car orconnected cars, smart grid, health care, smart appliances and advancedmedical services through convergence and combination between existinginformation technology (IT) and various industrial applications.

Various attempts have been made to apply 5G communication systems to IoTnetworks. For example, technologies such as a sensor network, MTC, andM2M communication may be implemented by beamforming, MIMO, and arrayantennas. Application of a cloud RAN as the above-described Big Dataprocessing technology may also be considered to be as an example ofconvergence between the 5G technology and the IoT technology.

Meanwhile, there is a need for a method and apparatus for transmittingdownlink control information in the next generation mobile communicationsystem in accordance with recent advances in long term evolution (LTE)and LTE-Advanced systems.

SUMMARY

The 5G wireless communication system, unlike existing wirelesscommunication systems, is intended to support not only servicesrequiring high data rates but also services having very shorttransmission latency and services requiring high connection density. Inthese scenarios, it is necessary to provide various services involvingdifferent transmission and reception techniques and parameters in onesystem for satisfying diverse requirements and needs of users, and it isimportant to design the system for forward compatibility so that theservices to be added are not constrained by the current system. The 5Gwireless communication system is designed to support multiplenumerologies for the subcarrier spacing so as to utilize time andfrequency resources more flexibly than the existing LTE system.

To achieve ultrahigh speed data services of up to several Gbps in the 5Gsystem, signals can be transmitted and received with an ultra-widebandwidth of several tens to several hundreds MHz or several GHz. Thesize of the bandwidth that can be supported by the terminal may be notthe same as the size of the system bandwidth. A specific bandwidth partcan be configured for the terminal to support signal transmission andreception. According to the relationship that power consumptionincreases in proportion to the transmission and reception bandwidth, toefficiently manage power consumption of the terminal or the base stationthrough adjustment of the transmission and reception bandwidth,bandwidth parts of different sizes can be configured for the operationof the terminal. To support subcarriers of different sizes, one or manybandwidth parts may be configured for the terminal, and the subcarrierspacing of the individual bandwidth parts may be set differently. Thebase station may configure bandwidth parts for the terminal, andtransmit and receive signals through the corresponding bandwidth partfor various purposes. The bandwidth part can be configured via varioussystem parameters.

To schedule data to be sent to the terminal, the base station maydetermine the bandwidth part to be used and transmit different downlinkcontrol information depending upon the configuration information of thecorresponding bandwidth part. More specifically, the base station canconfigure one or more bandwidth parts to the terminal, and can transmitsignals using one or more of the configured bandwidth parts. Thescheduling information for the data to be transmitted via each bandwidthpart may differ according to various system parameters, such asbandwidth size, slot duration and subcarrier spacing, set for thebandwidth part. Consequently, one or more different pieces of downlinkcontrol information can be transmitted.

Accordingly, an aspect of the disclosure is to provide a method fortransmitting downlink control information for efficient system operationin various signal transmission and reception operations using bandwidthparts. The base station may transmit downlink control information to theterminal for data transmission via the same bandwidth part. The basestation may transmit downlink control information to the terminal fordata transmission via a different bandwidth part. The base station maytransmit downlink control information to the terminal for datatransmission via multiple bandwidth parts. To support the operationsdescribed above, an additional downlink control information field may berequired, or different interpretations of the same downlink controlinformation field may be required. In consideration of this, thedisclosure provides a downlink control information field and provides amethod and apparatus for transmitting downlink control informationcorrespondingly.

In accordance with an aspect of the disclosure, a method performed by auser equipment is provided for communication in a communication systemsupporting one or more bandwidth parts. The method includes identifyinga first bandwidth part for a cell and a second bandwidth part for thecell through a radio resource control signaling, wherein each of thefirst bandwidth part and the second bandwidth part is defined with acorresponding subcarrier spacing and frequency domain location;identifying a first control resource set on the first bandwidth part anda second control resource set on the second bandwidth part through theradio resource control signaling; and acquiring second downlink controlinformation for the second bandwidth part based on the first controlresource set on the first bandwidth part being activated. A bandwidthpart indicator, a frequency domain resource assignment, and a timedomain resource assignment are included in the second downlink controlinformation. A number of bits of bandwidth part indicator is definedbased on the radio resource control signaling. The first bandwidth partis activated by first downlink control information. The first downlinkcontrol information and the second downlink control information areacquired in a user equipment specific control region.

In accordance with another aspect of the disclosure, a user equipment isprovided for communication in a communication system supporting one ormore bandwidth parts. The user equipment includes a transceiver; and acontroller coupled with the transceiver and configured to identify afirst bandwidth part for a cell and a second bandwidth part for the cellthrough a radio resource control signaling, wherein each of the firstbandwidth part and the second bandwidth part is defined with acorresponding subcarrier spacing and frequency domain location, identifya first control resource set on the first bandwidth part and a secondcontrol resource set on the second bandwidth part through the radioresource control signaling, and acquire second downlink controlinformation for the second bandwidth part based on the first controlresource set on the first bandwidth part being activated. A bandwidthpart indicator, a frequency domain resource assignment, and a timedomain resource assignment are included in the second downlink controlinformation. A number of bits of bandwidth part indicator is definedbased on the radio resource control signaling. The first bandwidth partis activated by first downlink control information. The first downlinkcontrol information and the second downlink control information areacquired in a user equipment specific control region.

In accordance with another aspect of the disclosure, a method performedby a base station is provided for communication in a communicationsystem supporting one or more bandwidth parts. The method includestransmitting a radio resource control signaling including informationfor a first bandwidth part for a cell and information for a secondbandwidth part for the cell, wherein each of the first bandwidth partand the second bandwidth part is defined with a corresponding subcarrierspacing and frequency domain location; identifying a first controlresource set on the first bandwidth part and a second control resourceset on the second bandwidth part through the radio resource controlsignaling; and transmitting second downlink control information for thesecond bandwidth part based on the first control resource set on thefirst bandwidth part being activated. A bandwidth part indicator, afrequency domain resource assignment, and a time domain resourceassignment are included in the second downlink control information. Anumber of bits of bandwidth part indicator is defined based on the radioresource control signaling. The first bandwidth part is activated byfirst downlink control information. The first downlink controlinformation and the second downlink control information are acquired ina user equipment specific control region.

In accordance with another aspect of the disclosure, a base station isprovided for communication in a communication system supporting one ormore bandwidth parts. The base station includes a transceiver; and acontroller coupled with the transceiver and configured to transmit aradio resource control signaling including information for a firstbandwidth part for a cell and information for a second bandwidth partfor the cell, wherein each of the first bandwidth part and the secondbandwidth part is defined with a corresponding subcarrier spacing andfrequency domain location, identify a first control resource set on thefirst bandwidth part and a second control resource set on the secondbandwidth part through the radio resource control signaling, andtransmit second downlink control information for the second bandwidthpart based on the first control resource set on the first bandwidth partbeing activated. A bandwidth part indicator, a frequency domain resourceassignment, and a time domain resource assignment are included in thesecond downlink control information. A number of bits of bandwidth partindicator is defined based on the radio resource control signaling. Thefirst bandwidth part is activated by first downlink control information.The first downlink control information and the second downlink controlinformation are acquired in a user equipment specific control region.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainembodiments of the disclosure will be more apparent from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram of the time-frequency domain in LTE, according to anembodiment;

FIG. 2 is a diagram of a physical downlink control channel (PDCCH) andenhanced PDCCH (EPDCCH) serving as a downlink control channel in longterm evolution (LTE), according to an embodiment;

FIG. 3 is a diagram of the 5G downlink control channel, according to anembodiment;

FIG. 4 is a diagram of a resource region allocation for the 5G downlinkcontrol channel, according to an embodiment;

FIG. 5 is a diagram of many subcarrier spacings considered in 5Gcommunication, according to an embodiment;

FIG. 6 is a diagram of bandwidth parts considered in 5G communication,according to an embodiment;

FIG. 7 is a diagram of a terminal, according to an embodiment; and

FIG. 8 is a diagram of a base station, according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the disclosure will be described herein below withreference to the accompanying drawings. However, the embodiments of thedisclosure are not limited to the specific embodiments and should beconstrued as including all modifications, changes, equivalent devicesand methods, and/or alternative embodiments of the present disclosure.In the description of the drawings, similar reference numerals are usedfor similar elements.

The terms “have,” “may have,” “include,” and “may include” as usedherein indicate the presence of corresponding features (for example,elements such as numerical values, functions, operations, or parts), anddo not preclude the presence of additional features.

The terms “A or B,” “at least one of A or/and B,” or “one or more of Aor/and B” as used herein include all possible combinations of itemsenumerated with them. For example, “A or B,” “at least one of A and B,”or “at least one of A or B” means (1) including at least one A, (2)including at least one B, or (3) including both at least one A and atleast one B.

The terms such as “first” and “second” as used herein may usecorresponding components regardless of importance or an order and areused to distinguish a component from another without limiting thecomponents. These terms may be used for the purpose of distinguishingone element from another element. For example, a first user device and asecond user device may indicate different user devices regardless of theorder or importance. For example, a first element may be referred to asa second element without departing from the scope the disclosure, andsimilarly, a second element may be referred to as a first element.

It will be understood that, when an element (for example, a firstelement) is “(operatively or communicatively) coupled with/to” or“connected to” another element (for example, a second element), theelement may be directly coupled with/to another element, and there maybe an intervening element (for example, a third element) between theelement and another element. To the contrary, it will be understoodthat, when an element (for example, a first element) is “directlycoupled with/to” or “directly connected to” another element (forexample, a second element), there is no intervening element (forexample, a third element) between the element and another element.

The expression “configured to (or set to)” as used herein may be usedinterchangeably with “suitable for,” “having the capacity to,” “designedto,” “adapted to,” “made to,” or “capable of” according to a context.The term “configured to (set to)” does not necessarily mean“specifically designed to” in a hardware level. Instead, the expression“apparatus configured to . . . ” may mean that the apparatus is “capableof . . . ” along with other devices or parts in a certain context. Forexample, “a processor configured to (set to) perform A, B, and C” maymean a dedicated processor (e.g., an embedded processor) for performinga corresponding operation, or a generic-purpose processor (e.g., acentral processing unit (CPU) or an application processor (AP)) capableof performing a corresponding operation by executing one or moresoftware programs stored in a memory device.

The terms used in describing the various embodiments of the disclosureare for the purpose of describing particular embodiments and are notintended to limit the disclosure. As used herein, the singular forms areintended to include the many forms as well, unless the context clearlyindicates otherwise. All of the terms used herein including technical orscientific terms have the same meanings as those generally understood byan ordinary skilled person in the related art unless they are definedotherwise. The terms defined in a generally used dictionary should beinterpreted as having the same or similar meanings as the contextualmeanings of the relevant technology and should not be interpreted ashaving ideal or exaggerated meanings unless they are clearly definedherein. According to circumstances, even the terms defined in thisdisclosure should not be interpreted as excluding the embodiments of thedisclosure.

The term “module” as used herein may, for example, mean a unit includingone of hardware, software, and firmware or a combination of two or moreof them. The “module” may be interchangeably used with, for example, theterm “unit”, “logic”, “logical block”, “component”, or “circuit”. The“module” may be a minimum unit of an integrated component element or apart thereof. The “module” may be a minimum unit for performing one ormore functions or a part thereof. The “module” may be mechanically orelectronically implemented. For example, the “module” according to thedisclosure may include at least one of an application-specificintegrated circuit (ASIC) chip, a field-programmable gate array (FPGA),and a programmable-logic device for performing operations which has beenknown or are to be developed hereinafter.

An electronic device according to the disclosure may include at leastone of, for example, a smart phone, a tablet personal computer (PC), amobile phone, a video phone, an electronic book reader (e-book reader),a desktop PC, a laptop PC, a netbook computer, a workstation, a server,a personal digital assistant (PDA), a portable multimedia player (PMP),a MPEG-1 audio layer-3 (MP3) player, a mobile medical device, a camera,and a wearable device. The wearable device may include at least one ofan accessory type (e.g., a watch, a ring, a bracelet, an anklet, anecklace, a glasses, a contact lens, or a head-mounted device (HMD)), afabric or clothing integrated type (e.g., an electronic clothing), abody-mounted type (e.g., a skin pad, or tattoo), and a bio-implantabletype (e.g., an implantable circuit).

The electronic device may be a home appliance. The home appliance mayinclude at least one of, for example, a television, a digital video disk(DVD) player, an audio, a refrigerator, an air conditioner, a vacuumcleaner, an oven, a microwave oven, a washing machine, an air cleaner, aset-top box, a home automation control panel, a security control panel,a TV box (e.g., Samsung IomeSync™, Apple TV™, or Google TV™), a gameconsole (e.g., Xbox™ and PlayStation™), an electronic dictionary, anelectronic key, a camcorder, and an electronic photo frame.

The electronic device may include at least one of various medicaldevices (e.g., various portable medical measuring devices (a bloodglucose monitoring device, a heart rate monitoring device, a bloodpressure measuring device, a body temperature measuring device, etc.), amagnetic resonance angiography (MRA), a magnetic resonance imaging(MRI), a computed tomography (CT) machine, and an ultrasonic machine), anavigation device, a global positioning system (GPS) receiver, an eventdata recorder (EDR), a flight data recorder (FDR), a vehicleinfotainment device, an electronic device for a ship (e.g., a navigationdevice for a ship, and a gyro-compass), avionics, security devices, anautomotive head unit, a robot for home or industry, an automatic tellermachine (ATM) in banks, point of sales (POS) devices in a shop, or anIoT device (e.g., a light bulb, various sensors, electric or gas meter,a sprinkler device, a fire alarm, a thermostat, a streetlamp, a toaster,a sporting goods, a hot water tank, a heater, a boiler, etc.).

The electronic device may include at least one of a part of furniture ora building/structure, an electronic board, an electronic signaturereceiving device, a projector, and various kinds of measuringinstruments (e.g., a water meter, an electric meter, a gas meter, and aradio wave meter). The electronic device may be a combination of one ormore of the aforementioned various devices. The electronic device mayalso be a flexible device. Further, the electronic device is not limitedto the aforementioned devices, and may include an electronic deviceaccording to the development of new technology.

Hereinafter, an electronic device will be described with reference tothe accompanying drawings. In the disclosure, the term “user” mayindicate a person using an electronic device or a device (e.g., anartificial intelligence electronic device) using an electronic device.

The following description is based on LTE and 5G systems. However, itshould be understood by those skilled in the art that the subject matterof the disclosure is applicable to other communication systems havingsimilar technical backgrounds and channel configurations withoutsignificant modifications departing from the scope of the disclosure.

In contrast to early wireless communication systems having providedvoice-oriented services only, advanced broadband wireless communicationsystems, such as 3GPP high speed packet access (HSPA) systems, LTE orevolved universal terrestrial radio access (E-UTRA) systems,LTE-advanced (LTE-A) systems, LTE Pro systems, 3GPP2 high rate packetdata (HRPD) systems, ultra mobile broadband (UMB) systems, and IEEE802.16e based systems, may provide high-speed and high-quality packetdata services.

In the LTE system as a representative example of a wideband wirelesscommunication system, orthogonal frequency division multiplexing (OFDM)is used for the downlink and single carrier frequency division multipleaccess (SC-FDMA) is used for the uplink. The uplink refers to a radiolink through which a terminal (user equipment (UE) or mobile station(MS)) sends a data or control signal to a base station (BS or eNode B),and the downlink refers to a radio link through which a base stationsends a data or control signal to a terminal. In such multiple accessschemes, time-frequency resources used to carry user data or controlinformation are allocated so as not to overlap each other (i.e. maintainorthogonality) to thereby identify the data or control information of aspecific user.

As a post-LTE communication system, the 5G communication system shouldbe able to support services satisfying various requirements inconsideration of various needs of users and service providers. The 5Gcommunication system can be designed to support enhanced mobilebroadband (eMBB), massive machine type communication (mMTC), and ultrareliable and low latency communications (URLLC).

eMBB provides a higher data rate than that supported by the existingLTE, LTE-A or LTE-Pro system. For eMBB in the 5G communication system,the base station should be able to provide a peak data rate of 20 Gbpsin the downlink and a peak data rate of 10 Gbps in the uplink. The 5Gcommunication system provides an increased user perceived data rate forthe terminal. Satisfying these requirements requires improvements invarious transmission and reception techniques including improved MIMOtechnology. While the current LTE system transmits signals using amaximum transmission bandwidth of 20 MHz in the 2 GHz band, the 5Gcommunication system may meet the required data transmission rate byusing a transmission bandwidth greater than 20 MHz in the bands offrequencies between 3 and 6 GHz or 6 GHz and higher.

In the 5G communication system, mMTC supports application services suchas the IoT. For efficient support of IoT services, mMTC is required tosupport a massive number of terminals in a cell, extend the coverage forthe terminal, lengthen the battery time for the terminal, and reduce thecost of the terminal. The IoT must be able to support a massive numberof terminals (e.g., 1,000,000 terminals/km²) in a cell to provide acommunication service to sensors and components attached to variousdevices. In addition, due to the nature of the service, mMTC is morelikely to cover shadow areas such as the basement of a building and anarea that a cell cannot cover, thus requiring a coverage wider than thatprovided by other 5G services. Low-cost terminals are likely to be usedin mMTC, and a very long battery lifetime (e.g., 10 to 15 years) isrequired because it is difficult to frequently replace the battery of aterminal.

URLLC, as cellular-based mission-critical wireless communication for aspecific purpose, is a service usable for remote control of robots ormachinery, industrial automation, unmanned aerial vehicles, remotehealth care, and emergency notification, and should enableultra-reliable and low-latency communication. A URLLC service may haveto support both an air interface latency of less than 0.5 ms and apacket error rate of 10⁻⁵ or less as a requirement. Hence, for URLLC,the transmission time interval (TTI) should be shorter than that ofother 5G services, and resources should be allocated in a wide frequencyband for the reliability of communication links.

The three 5G services (i.e., eMBB, URLLC, and mMTC) can be multiplexedand transmitted in one system. Here, to satisfy different requirements,different transmission and reception techniques and parameters can beused for the 5G services.

FIG. 1 is a diagram of the time-frequency domain serving as radioresources to transmit data or control channels in the downlink of theLTE system, according to an embodiment.

In FIG. 1, the horizontal axis denotes the time domain and the verticalaxis denotes the frequency domain. In the time domain, the minimum unitfor transmission is OFDM symbols. N_(symb) OFDM symbols 101 constituteone slot 102, and two slots constitute one subframe 103. The length of aslot is 0.5 ms and the length of a subframe is 1.0 ms. The radio frame(or frame) 104 is a time domain unit composed of 10 subframes. In thefrequency domain, the minimum unit for transmission is subcarriers, andthe total system transmission bandwidth is composed of a total N_(BW)subcarriers 105. The basic unit of resources in the time-frequencydomain is a resource element (RE) 106. The RE may be represented by anOFDM symbol index and a subcarrier index. A resource block (RB, orphysical resource block (PRB)) 107 is defined by N_(symb) consecutiveOFDM symbols 101 in the time domain and N_(RB) consecutive subcarriers108 in the frequency domain. Hence, one RB 107 is composed ofN_(symb)×N_(RB) REs 106. The minimum unit for data transmission is anRB. In the LTE system, N_(symb) is set to 7 and N_(RB) is set to 12, andN_(BW) and N_(RB) are proportional to the bandwidth of the systemtransmission band.

In the LTE system, scheduling information for downlink data or uplinkdata is sent by the base station to the terminal through downlinkcontrol information (DCI). Various DCI formats are defined. The DCIformat to be used may be determined according to various parametersrelated to scheduling information for uplink data, schedulinginformation for downlink data, compact DCI with a small size, spatialmultiplexing using multiple antennas, and power control DCI. Forexample, DCI format 1 for scheduling information of downlink data isconfigured to include at least the following pieces of controlinformation.

-   -   Resource allocation type 0/1 flag: this indicates whether the        resource allocation scheme is type 0 or type 1. Type 0 indicates        resource allocation in units of RB groups (RBG) by use of a        bitmap. In the LTE system, the basic scheduling unit is an RB        represented as a time-frequency domain resource. An RBG        including multiple RBs is the basic scheduling unit for type 0.        Type 1 indicates allocation of a specific RB in one RBG.    -   Resource block assignment: this indicates an RB allocated for        data transmission. The resource represented by RB assignment is        determined according to the system bandwidth and resource        allocation scheme.    -   Modulation and coding scheme (MCS): this indicates the        modulation scheme applied for data transmission and the        transport block (TB) size for data to be sent.    -   Hybrid automatic repeat request (HARQ) process number: this        indicates the process number of the corresponding HARQ process.    -   New data indicator: this indicates either initial transmission        or retransmission for HARQ.    -   Redundancy version: this indicates the redundancy version for        HARQ.    -   TPC (transmit power control) command for PUCCH: this indicates a        TPC command for the physical uplink control channel (PUCCH)        serving as an uplink control channel.

The DCI is channel coded, modulated, and sent through the PDCCH orEPDCCH.

A cyclic redundancy check (CRC) is attached to the DCI message payload,and the CRC is scrambled with a radio network temporary identifier(RNTI) corresponding to the identity of a terminal. Different RNTIs areused depending on the purpose of the DCI message, e.g.,terminal-specific data transmission, power control command, or randomaccess response. That is, the RNTI is not explicitly transmitted but isincluded in the CRC calculation for transmission. Upon receiving a DCImessage transmitted on the PDCCH, the terminal uses the allocated RNTIto check the CRC. If the CRC check is successful, the terminal is awarethat the DCI message is transmitted to it.

The LTE system supports three types of resource allocation (type 0, type1, and type 2) for the PDSCH.

In resource allocation type 0, non-consecutive RB allocation in thefrequency domain is supported, and a bitmap is used to indicate theallocated RBs. When the allocated RBs are indicated by a bitmap with thesame size as the number of RBs, it may be necessary to transmit a verylarge bitmap as to a large cell bandwidth, resulting in a high controlsignaling overhead. In resource allocation type 0, the size of thebitmap is reduced by grouping those RBs consecutive in the frequencydomain and pointing to the groups without pointing to the individualRBs. When the total transmission bandwidth is N_(RB) and the number ofRBs per RBG is P, the bitmap necessary to notify RB allocationinformation in resource allocation type 0 becomes ┌N_(RB)/P┐. If thenumber of RBs per RBG (i.e., P) is small, scheduling flexibility isincreased, but the control signaling overhead is increased. The P valueshould be selected appropriately so as to reduce the number of bitsrequired while maintaining sufficient resource allocation flexibility.In LTE, the RBG size is determined by the downlink cell bandwidth, andpossible RBG sizes are shown in Table 1 below.

TABLE 1 System Bandwidth N_(RB) ^(DL) RBG Size (P) ≤10 1 11-26 2 27-63 3 64-110 4

In resource allocation type 1, resource allocation is performed bydividing the entire RBG set into RBG subsets scattered in the frequencydomain. The number of subsets is given by the cell bandwidth, and thenumber of subsets in resource allocation type 1 is equal to the RBG size(P) in resource allocation type 0. The RB allocation information inresource allocation type 1 is composed of three fields described below.

-   -   A first field indicating the selected RBG subset (┌log₂(P)┐        bits).    -   A second field indicating the shift of resource allocation in        the subset (1 bit).    -   A third field indicating the bitmap for the allocated RBG        (┌N_(RB)/P┐−┌log₂(P)┐−1 bits).

As a result, the total number of bits used in resource allocation type 1becomes ┌N_(RB)/P┐, which is equal to the number of bits required inresource allocation type 0. A 1-bit indicator is added to notify theterminal of whether the resource allocation type is 0 or 1.

Resource allocation type 2 does not depend on a bitmap, unlike the tworesource allocation types described above. Instead, the resourceallocation is indicated by the start point of the RB allocation andlength thereof. Resource allocation types 0 and 1 supportnon-consecutive RB allocation, while resource allocation type 2 supportsonly sequential RB allocation. As a result, the RB allocationinformation in resource allocation type 2 is composed of two fieldsdescribed below.

-   -   A first field indicating the RB start point (RB_(start)).    -   A second field indicating the length of consecutively allocated        RBs (L_(CRBs)).

In resource allocation type 2, total ┌log₂(N_(RB)(N_(RB)+1)/2)┐ bits areused.

All three resource allocation types are related to virtual RB (VRBs). Inresource allocation types 0 and 1, the VRBs are mapped directly to thephysical resource blocks in a localized form. Resource allocation type 2supports both localized VRBs and distributed VRBs. In resourceallocation type 2, there is an additional indicator to indicatinglocalized or distributed VRBs.

FIG. 2 is a diagram of a PDCCH 201 and an enhanced PDCCH (EPDCCH) 202serving as downlink physical channels through which the DCI istransmitted in LTE, according to an embodiment.

In FIG. 2, the PDCCH 201 is time-multiplexed with the PDSCH 203 servingas a data transmission channel and is transmitted over the overallsystem bandwidth. The region of the PDCCH 201 is represented by thenumber of OFDM symbols, and the number of OFDM symbols is notified tothe terminal via a control format indicator (CFI) transmitted throughthe physical control format indicator channel (PCFICH). The PDCCH 201 isallocated to the first OFDM symbols of the subframe so that the terminalcan decode the downlink scheduling assignment as soon as possible. Thiscan reduce the decoding delay for the downlink shared channel (DL-SCH),i.e., the overall downlink transmission delay. Since one PDCCH carriesone DCI message and a plurality of terminals can be scheduledsimultaneously in the downlink and uplink, multiple PDCCHs aresimultaneously transmitted in each cell. The CRS (cell specificreference signal) 204 is used as a reference signal for decoding thePDCCH 201. The CRS 204 is transmitted every subframe over the entirebandwidth, and scrambling and resource mapping are changed according tothe cell ID (identity). Since the CRS 204 is a reference signal commonto all terminals, terminal-specific beamforming cannot be used. In LTE,multiple antenna transmission for the PDCCH is limited to open looptransmit diversity. The number of CRS ports is implicitly notified tothe terminal from the decoding of the physical broadcast channel (PBCH).

The resource allocation for the PDCCH 201 is based on a control channelelement (CCE), and one CCE is composed of 9 resource element groups(REGs) (i.e., 36 resource elements (REs)). The number of CCEs requiredfor a particular PDCCH 201 may be 1, 2, 4, or 8 depending on the channelcoding rate of the DCI message payload. Different numbers of CCEs areused to implement the link adaptation of the PDCCH 201. The terminalshould detect a signal in a state where it does not know informationabout the PDCCH 201. A search space indicating a set of CCEs for blinddecoding is specified in LTE. The search space is composed of a set ofCCEs for each aggregation level, and is not explicitly signaled butimplicitly specified by a function of the terminal identity and thesubframe number. The terminal performs decoding of the PDCCH 201 for allpossible resource candidates that can be generated from the CCEs in thesearch space set in each subframe, and processes the information foundto be valid to the terminal through the CRC check.

The search space is classified into a terminal-specific search space anda common search space. Some or all terminals in a certain group canexamine the common search space of the PDCCH 201 to receive controlinformation common to the cell such as dynamic scheduling of the systeminformation and paging messages. The scheduling assignment informationof the DL-SCH for transmission of system information block 1 (SIB-1)including the cell operator information can be received by checking thecommon search space of the PDCCH 201.

In FIG. 2, the EPDCCH 202 is frequency-multiplexed with the PDSCH 203for transmission. The base station can appropriately allocate resourcesfor the EPDCCH 202 and the PDSCH 203 through scheduling and effectivelysupport the coexistence with data transmissions for the existing LTEterminal. However, since the EPDCCH 202 is transmitted over one entiresubframe in the time domain, there is a loss in terms of transmissiondelay. A plurality of EPDCCHs 202 constitute one EPDCCH set, andallocation of an EPDCCH set is performed on a PRB pair basis. Thelocation information for the EPDCCH set is terminal-specificallyconfigured and is signaled via RRC (radio resource control). Up to twoEPDCCH sets may be configured for a terminal, and one EPDCCH set may beconfigured for different terminals at the same time in a multiplexedfashion.

The resource allocation of the EPDCCH 202 is based on the ECCE (enhancedCCE), one ECCE can be composed of four or eight enhanced REGs (EREGs),and the number of EREGs per ECCE depends on the cyclic prefix (CP)length and the subframe configuration information. One EREG is composedof 9 REs, and there can be 16 EREGs per PRB pair. EPDCCH transmissionmay be localized or distributed according to the RE mapping scheme ofthe EREG. The ECCE aggregation level can be 1, 2, 4, 8, 16, or 32, andis determined according to the CP length, subframe configuration, EPDCCHformat, and transmission scheme.

The EPDCCH 202 supports only the terminal-specific search space. Hence,a terminal wishing to receive a system message must examine the commonsearch space on the existing PDCCH 201.

In the EPDCCH 202, a demodulation reference signal (DMRS) 205 is used asa reference signal for decoding. Precoding for the EPDCCH 202 can beconfigured by the base station and use terminal-specific beamforming.Through the DMRS 205, the terminals can perform decoding on the EPDCCH202 without knowing what precoding is used. The EPDCCH 202 uses the samepattern as the DMRS of the PDSCH 203. However, unlike the PDSCH 203, theDMRS 205 in the EPDCCH 202 can support transmission using up to fourantenna ports. The DMRS 205 is transmitted only in the corresponding PRBin which the EPDCCH is transmitted.

The port configuration information of the DMRS 205 depends on thetransmission scheme of the EPDCCH 202. For localized transmission, theantenna port corresponding to the ECCE to which the EPDCCH 202 is mappedis selected based on the ID of the terminal. If different terminalsshare the same ECCE (i.e., multiuser MIMO transmission is used), theDMRS antenna port can be assigned to each terminal. Alternatively,transmission may be performed by sharing the DMRS 205. It can bedistinguished according to the DMRS scrambling sequence which is set byhigher layer signaling. For distributed transmission, up to two antennaports are supported for the DMRS 205, and a diversity scheme of precodercycling is supported. The DMRS 205 may be shared for all REs transmittedwithin one PRB pair.

In LTE, the entire PDCCH region is composed of a logical set of CCEs andincludes a search space composed of a set of CCEs. The search space maybe a common search space or a terminal-specific search space. The searchspace for the LTE PDCCH is defined as follows.

The set of PDCCH candidates to monitor are defined in terms of searchspaces, where a search space S_(k) ^((L)) at aggregation level L∈{1, 2,4, 8} is defined by a set of PDCCH candidates. For each serving cell onwhich PDCCH is monitored, the CCEs corresponding to PDCCH candidate m ofthe search space S_(k) ^((L)) are given by Equation (1):

L{(Y _(k) +m′)mod└N _(CCE,k) /L┘}+i  (1)

where Y_(k) is defined below, i=0, . . . , L−1. For the common searchspace m′=m. For the PDCCH UE specific search space, for the serving cellon which PDCCH is monitored, if the monitoring UE is configured withcarrier indicator field then m′=m+M^((L))·n_(CI) where n_(CI) is thecarrier indicator field value, else if the monitoring UE is notconfigured with carrier indicator field then m′=m, where m=0, . . . ,M^((L))−1. M^((L)) is the number of PDCCH candidates to monitor in thegiven search space.

Note that the carrier indicator field value is the same as ServCellIndex

For the common search spaces, Y_(k) is set to 0 for the two aggregationlevels L=4 and L=8.

For the UE-specific search space S_(k) ^((L)) at aggregation level L,the variable Y_(k) is defined by Equation (2):

Y _(k)=(A·Y _(k-1))mod D  (2)

where Y⁻¹=n_(RNTI)≠0, A=39827, D=65537 and k=└n_(s)/2┘, n_(s) is theslot number within a radio frame.

The RNTI value used for n_(RNTI) is defined in subclause 7.1 in downlinkand subclause 8 in uplink.

According to the definition of the search space for the PDCCH describedabove, the terminal-specific search space is implicitly defined througha function of the terminal identity and the subframe number withoutbeing explicitly signaled. In other words, since the terminal-specificsearch space can be changed according to the subframe number, theterminal-specific search space can be changed over time, which solvesthe problem that a specific terminal cannot use the search space due toother terminals (blocking problem). Although a specific terminal cannotbe scheduled in a given subframe because all the CCEs are used by otherterminals scheduled in the same subframe, since the search space varieswith time, such a problem may not occur in the next subframe. Forexample, although the terminal-specific search space of terminal #1 andthe terminal-specific search space of terminal #2 partially overlap in aspecific subframe, as the terminal-specific search space changes foreach subframe, it can be expected that the overlap in the next subframewill be different.

According to the definition of the search space for the PDCCH describedabove, the common search space is defined as a set of pre-agreed CCEsbecause a certain group of terminals or all terminals must receive thePDCCH. The common search space does not vary according to the terminalidentity or the subframe number. The common search space is used totransmit various system messages, but it can also be used to transmitcontrol information of a specific terminal. As such, the common searchspace may be a solution to the problem that the terminal cannot bescheduled due to a lack of available resources in the terminal-specificsearch space.

The search space at a given aggregation level is a set of candidatecontrol channels composed of CCEs where the terminal should attemptdecoding. Since there are several aggregation levels that create onegroup with 1, 2, 4, and 8 CCEs, the terminal has multiple search spaces.The number of PDCCH candidates to be monitored by the terminal in thesearch space at a given aggregation level in the LTE PDCCH is defined asshown in Table 2 below.

TABLE 2 Search space S_(k) ^((L)) Number of PDCCH Type Aggregationlevel^(L) Size [in CCEs] candidates M^((L)) UE- 1 6 6 specific 2 12 6 48 2 8 16 2 Common 4 16 4 8 16 2

According to Table 2, for the terminal-specific search space, {1, 2, 4,8}aggregation levels are supported with {6, 6, 2, 2} PDCCH candidates,respectively. For the common search space, {4, 8} aggregation levels aresupported with {4, 2} PDCCH candidates, respectively. The reason thatthe common search space supports only aggregation levels {4, 8} is toimprove the coverage characteristics because system messages generallyhave to reach the edge of the cell.

The DCI transmitted via the common search space is defined only for someDCI formats such as 0/1A/3/3A/1C, which are used for system messages orpower control for terminal groups. The DCI format with spatialmultiplexing is not supported in the common search space. The downlinkDCI format to be decoded in the terminal-specific search space variesdepending on the transmission mode set for the corresponding terminal.Since the transmission mode is set through RRC signaling, the accuratesubframe number is not specified as to whether the setting is effectivefor the terminal. The terminal can operate so as not to lose thecommunication by always decoding DCI format IA regardless of thetransmission mode.

A description has been given above of transmitting the downlink controlchannel and the search space in the existing LTE or LTE-A system.

Next, a description is given of the downlink control channel in the 5Gcommunication system.

FIG. 3 is a diagram of time-frequency resources constituting a downlinkcontrol channel usable in a 5G communication system, according to anembodiment. In FIG. 3, the basic unit (REG 303, or new radio (NR) REG(NR-REG 303)) of the time-frequency resources constituting the controlchannel is composed of one OFDM symbol 301 in the time domain and 12subcarriers 302 (i.e., 1 RB) in the frequency domain. In the basic unitof the control channel, by assuming that the time-domain unit is oneOFDM symbol 301, the data channel and the control channel can betime-multiplexed within one subframe. By placing the control channelahead of the data channel, the processing time of the user can bereduced, facilitating satisfaction of the latency requirement. Bysetting the frequency-domain unit of the control channel to 1 RB (302),frequency multiplexing between the control channel and the data channelcan be performed more efficiently.

By concatenating the NR-REGs 303 shown in FIG. 3, control channelregions of various sizes can be configured. When the basic unit forallocation of the downlink control channel in the 5G system is a NR-CCE304, one NR-CCE 304 may be composed of many NR-REGs 303. The NR-REG 303shown in FIG. 3 may be composed of 12 REs, and if one NR-CCE 304 iscomposed of 4 NR-REGs 303, one NR-CCE 304 may be composed of 48 REs.When a downlink control region is configured, the downlink controlregion may be composed of many NR-CCEs 304, and a specific downlinkcontrol channel may be mapped to one NR-CCE 304 or many NR-CCEs 304 inthe control region for transmission according to the aggregation level.The NR-CCEs 304 in the control region are identified by their numbers,and the numbers can be assigned according to the logical mapping scheme.

The basic unit of the downlink control channel shown in FIG. 3 (i.e.,NR-REG 303) may include the REs to which the DCI is mapped and a regionto which the DMRS 305 serving as a reference signal for decoding the DCIis mapped. The DMRS 305 can be efficiently transmitted in considerationof the overhead due to the RS assignment. When the downlink controlchannel is mapped for transmission to a plurality of OFDM symbols, theDMRS 305 may be mapped for transmission only to the first OFDM symbol.The DMRS 305 may be mapped in consideration of the number of antennaports used to transmit the downlink control channel. In FIG. 3, twoantenna ports are used, but the disclosure is not so limited. There maybe a DMRS 306 transmitted for antenna port #0 and a DMRS 307 transmittedfor antenna port #1. The DMRSs for different antenna ports can bemultiplexed in various ways. In FIG. 3, DMRSs corresponding to differentantenna ports are orthogonally transmitted via different REs. The DMRSscan be frequency division multiplexed (FDMed) or code divisionmultiplexed (CDMed) for transmission. There may be various other DMRSpatterns in association with the number of antenna ports. In thefollowing description of the embodiments, it is assumed that two antennaports are used. The same principle may be applied to the cases where twoor more antenna ports are used.

FIG. 4 is a diagram of a control region (control resource set (CORESET))in which the downlink control channel is transmitted in the 5G wirelesscommunication system, according to an embodiment.

In FIG. 4, there are the system bandwidth 410 in the frequency domainand one slot 420 in the time domain (one slot is assumed to include 7OFDM symbols). The overall system bandwidth 410 may be composed ofmultiple bandwidth parts (e.g., 4 four bandwidth parts in FIG. 4including bandwidth part #1 (402), bandwidth part #2 (403), bandwidthpart #3 (404), and bandwidth part #4 (405)).

In FIG. 4, two control regions (control region #1 (440) and controlregion #2 (450)) are configured. In the frequency domain, the controlregions 440 and 450 may be set over specific sub-bands within theoverall system bandwidth 410.

Control region #1 (440) is configured over bandwidth part #1 (402) andbandwidth part #2 (403), and control region #2 (450) is configuredwithin bandwidth part #4 (405). In the time domain, the control regionmay include one or many OFDM symbols, and the number of such OFDMsymbols may be referred to as the control region length (controlresource set duration 460 or 470). In FIG. 4, control region #1 (440) isconfigured to have control region length #1 of 2 symbols, and controlregion #2 (470) is configured to have control region length #2 of 1symbol.

In the 5G communication system, a plurality of control regions can beconfigured in one system from the base station perspective. Also, aplurality of control regions can be configured for one terminal from theterminal perspective. Some of the control regions configured in thesystem can be set for the terminal. Consequently, the terminal may beunaware of a specific control region existing in the system. In FIG. 4,two control regions (control region #1 (440) and control region #2(450)) are configured in the system, and control region #1 (440) can beassigned to terminal #1 and control region #1 (440) and control region#2 (450) can be assigned to terminal #2. If there is no additionalindicator, terminal #1 may be unaware of the existence of control region#2 (450).

The control region in the above-described 5G system may be configured asa common control region, terminal-group common control region, orterminal-specific control region. The control region may be configuredfor a terminal through terminal-specific signaling, terminal-groupcommon signaling, or RRC signaling. Configuring the control region forthe terminal means providing information related to the location of thecontrol region, the sub-band, resource allocation of the control region,and the control region length. The base station may provide thefollowing information.

TABLE 3 Configuration information 1. Frequency domain RB allocationinformation Configuration information 2. Time domain control regionlength (number of symbols assigned to control region, start symbol)Configuration information 3. Resource mapping scheme (time- firstmapping, frequency-first mapping) Configuration information 4.Transmission mode (interleaved transmission mode, non-interleavedtransmission mode) Configuration information 5. Search space type(common search space, group-common search space, terminal-specificsearch space) Configuration information 6. Monitoring occasion(monitoring period/interval, monitoring symbol location in slot)Configuration information 7. DMRS configuration information (DMRSconfiguration, number of DMRS ports) Configuration information 8. REGbundling size

In addition to the above configuration information, other informationnecessary for transmitting the downlink control channel may beconfigured for the terminal.

In the 5G communication system, it is necessary to flexibly define andoperate the frame structure in consideration of various services andrequirements. For example, individual services may have differentsubcarrier spacings depending on their requirements. Currently, twoschemes are being considered to support a plurality of subcarriers inthe 5G communication system. As a first scheme for supporting aplurality of subcarriers in the 5G communication system, a set ofsubcarrier spacings that the 5G communication system can have may bedetermined using Equation (3) below.

Δf=f ₀2^(m)  (3)

Here, f₀ represents the basic subcarrier spacing of the system, and mrepresents an integer scaling factor. If f₀ is 15 kHz, the set ofsubcarrier spacings that the 5G communication system can have mayinclude 7.5 KHz, 15 KHz, 30 KHz, 60 KHz, 120 KHz, and the like. Thesystem can be configured by using all or some elements of the subcarrierspacing set given by Equation (3). It is assumed that a subcarrierspacing set {15 KHz, 30 KHz, 60 KHz} with f₀=15 kHz is used in the 5Gcommunication system according to the scheme described above. However,the technique proposed herein can be applied without limitation to thecase with a different subcarrier spacing set (e.g., {17.5 KHz, 35 KHz,70 KHz} with f₀=17.5 KHz). If a subcarrier spacing set {17.5 KHz, 35KHz, 70 KHz} is considered, this subcarrier spacing set may be mappedwith respect to the description based on f₀=15 kHz. Likewise, asubcarrier spacing set based on 35 kHz, 70 kHz, or 140 kHz may be mappedto another subcarrier spacing set based on 30 kHz, 60 kHz, or 120 kHz,respectively.

FIG. 5 shows resource elements 500 for subcarrier spacings Δf₁ (601),Δf₂ (502), Δf₃ (503), respectively. The subcarrier spacings Δf₁ (501),Δf₂ (502) and Δf₃ (503) correspond respectively to 15 kHz, 30 kHz and 60kHz. Each resource element has an OFDM symbol length of T_(s) (504),T_(s)′ (505), or T_(s)″ (506). As characteristics of OFDM symbols, thesubcarrier spacing and the OFDM symbol length have a reciprocalrelationship, and it can be confirmed that the symbol length shortenswhen the subcarrier spacing increases. That is, the value of T_(s) (504)is twice the value of T_(s)′ (505) and is four times the value of T_(s)″(506).

FIG. 6 is a diagram of bandwidth parts considered in 5G communication,according to an embodiment.

The base station can configure one or more bandwidth parts for theterminal. In FIG. 6, two bandwidth parts (i.e., bandwidth part #1 (610)and bandwidth part #2 (611)) are configured in the terminal bandwidth601.

The base station can specify the location and bandwidth size of eachbandwidth part for the terminal. In FIG. 6, bandwidth part #1 (610) islocated at center frequency #1 (604) and has a bandwidth size ofbandwidth #1 (602), and bandwidth part #2 (611) is located at centerfrequency #2 (605) and has a bandwidth size of bandwidth #2 (603). Thelocation of a bandwidth part can be set in various ways, e.g., bynotifying the offset of a reference point within the terminal bandwidthor system bandwidth. The size of a bandwidth part can be set in variousways, e.g., by notifying the number of RBs present in the bandwidthpart.

The base station can set the numerology (e.g., subcarrier spacing) ofeach bandwidth part for the terminal. In FIG. 6, the subcarrier spacingof bandwidth part #1 (610) is set to Δf₁ (=15 kHz, 608) and thesubcarrier spacing of bandwidth part #2 (611) is set to Δf₂ (=30 kHz,609). The slot duration of a bandwidth part can be changed according tothe subcarrier spacing. The slot duration may be varied not only by thesubcarrier spacing but also by the number of OFDM symbols constitutingthe slot. One slot may be composed of 7 OFDM symbols or 14 OFDM symbols.The base station can set information on the slot duration of eachbandwidth part (i.e., information on the number of OFDM symbolsconstituting the slot (7 OFDM symbols or 14 OFDM symbols)). Bandwidthpart #1 (610) is configured to have slot duration #1 (=7 OFDM symbols,606), and bandwidth part #2 (611) is configured to have slot duration #2(=14 OFDM symbols, 607).

The base station can configure a control region (control resource set)for the downlink control channel to transmit and receive the DCI foreach bandwidth part of the terminal. The base station may configurecontrol region #1 (612) as the control region for transmitting the DCIfor bandwidth part #1 (610), and configure control region #2 (613) asthe control region for transmitting the DCI for bandwidth part #2 (611).To receive the DCI for a specific bandwidth part, the terminal canexamine the corresponding control region set in the bandwidth part. Toconfigure a control region for a bandwidth part, the base station maynotify the terminal of all or some of the system parameters listed inTable 3, for example.

The base station may transmit the terminal configuration information forthe bandwidth part through higher layer signaling (e.g., RRC signaling).

As described before, to achieve ultrahigh speed data services of up toseveral Gbps in the 5G system, signals can be transmitted and receivedwith an ultra-wide bandwidth of several tens to several hundreds MHz orseveral GHz. The size of the bandwidth that can be supported by theterminal may be not the same as the size of the system bandwidth. Aspecific bandwidth part can be configured for the terminal to supportsignal transmission and reception.

To schedule data to be transmitted to the terminal, the base station maydetermine the bandwidth part to be used for transmission and transmitdifferent DCIs according to the configuration information of thebandwidth part. More specifically, the base station can configure one ormore bandwidth parts for the terminal and can transmit signals by usingone or more of the configured bandwidth parts. The schedulinginformation for data to be transmitted via each bandwidth part may bedifferent according to various system parameters set for the bandwidthpart, such as bandwidth size, slot duration and subcarrier spacing.Hence, one or more different DCIs can be transmitted.

In accordance with the disclosure, a DCI transmission method forefficient system operation in various signal transmission and receptionoperations using bandwidth parts can be provided. The base station maytransmit the DCI to the terminal for data transmission via the samebandwidth part. The base station may transmit the DCI to the terminalfor data transmission via a different bandwidth part. The base stationmay transmit the DCI to the terminal for data transmission via multiplebandwidth parts. To support the operations described above, anadditional DCI field may be required, or different interpretations ofthe same DCI field may be required.

Embodiment 1

The first embodiment of the disclosure provides a method and apparatusfor transmitting and receiving the DCI.

The base station may configure one or more bandwidth parts for theterminal. Each bandwidth part may be configured with different systemparameters such as subcarrier spacing, bandwidth size, RBG size, andslot duration.

The base station may transmit the terminal an indicator for activatingor deactivating one or more of the configured bandwidth parts, and thebase station and the terminal can transmit and receive signals via theactivated bandwidth part. This indicator may be notified by the basestation to the terminal through higher layer signaling (e.g., RRCsignaling or medium access control (MAC) control element (CE) signaling)or L1 signaling (e.g., common DCI, group-common DCI, orterminal-specific DCI).

The base station can configure a control region (control resource set)for the downlink control channel in each bandwidth part configured forthe terminal, and can transmit the DCI for the bandwidth part via thecorresponding control region.

More specifically with reference to FIG. 6, the base station canconfigure bandwidth part #1 (602) and bandwidth part #2 (603) for theterminal, and can configure control region #1 (612) and control region#2 (613) for bandwidth part #1 (602) and bandwidth part #2 (603),respectively. The base station may transmit the DCI for bandwidth part#1 (602) via control region #1 (612) and transmit the DCI for bandwidthpart #2 (603) via control region #2 (613).

The terminal may receive configuration information for one or morebandwidth parts from the base station. The terminal may receiveconfiguration information for the control region associated with eachbandwidth part from the base station. The terminal may receive anindicator for activating or deactivating one or more of the configuredbandwidth parts from the base station. The terminal can receive the DCIfor the corresponding bandwidth part via the control regions associatedwith one or more activated bandwidth parts.

Embodiment 2

The second embodiment of the disclosure provides a method and apparatusfor transmitting and receiving the DCI.

The base station may configure one or more bandwidth parts for theterminal.

The base station may transmit to the terminal an indicator foractivating or deactivating one or more of the configured bandwidthparts, and the base station and the terminal can transmit and receivesignals via the activated bandwidth part.

The base station can configure a control region (control resource set)for the downlink control channel in each bandwidth part configured forthe terminal, and can transmit the DCI for the bandwidth part via thecorresponding control region.

The base station may also transmit the DCI for one or more differentbandwidth parts via the control region of one or more activatedbandwidth parts. The base station may configure the terminal withinformation regarding the bandwidth part whose control region is to beused to transmit the DCI for another bandwidth part through higher layersignaling such as RRC or MAC CE signaling.

The terminal may receive configuration information for one or morebandwidth parts from the base station. The terminal may receiveconfiguration information for the control region associated with eachbandwidth part from the base station. The terminal may receiveconfiguration information regarding the control region of a specificbandwidth part to be used to receive the DCI for another bandwidth part.The terminal may receive an indicator for activating or deactivating oneor more of the configured bandwidth parts from the base station. Theterminal can receive the DCI for the corresponding bandwidth part oranother bandwidth part via the control region associated with one ormore activated bandwidth parts.

More specifically with reference to FIG. 6, the base station canconfigure the terminal with bandwidth part #1 (602) and bandwidth part#2 (603), and can configure control region #1 (612) and control region#2 (613) for bandwidth part #1 (602) and bandwidth part #2 (603),respectively.

The base station may configure the terminal with configurationinformation indicating that the DCI for bandwidth part #1 (602) istransmitted via control region #1 (612) and the DCI for bandwidth part#2 (603) is transmitted via control region #2 (613), and may perform DCItransmission according to the configuration information. Based on theconfiguration information from the base station, the terminal maymonitor control region #1 (612) to receive the DCI for bandwidth part #1(602), and monitor control region #2 (613) to receive the DCI forbandwidth part #2 (603).

The base station may also configure the terminal with configurationinformation indicating that the DCI for bandwidth part #1 (602) andbandwidth part #2 (603) is transmitted via control region #1 (612), andmay perform DCI transmission according to the configuration information.Based on the configuration information from the base station, theterminal may monitor control region #1 (612) to receive the DCI forbandwidth part #1 (602) and the DCI for bandwidth part #2 (603).

The base station may also configure the terminal with configurationinformation indicating that the DCI for bandwidth part #1 (602) andbandwidth part #2 (603) is transmitted via control region #2 (613), andmay perform DCI transmission according to the configuration information.Based on the configuration information from the base station, theterminal may monitor control region #2 (613) to receive the DCI forbandwidth part #1 (602) and the DCI for bandwidth part #2 (603).

The following terms will be defined for ease of description of theembodiments of the disclosure.

-   -   Self scheduling: indicates that the DCI indicating data        scheduling and the scheduled data are transmitted via the same        bandwidth part. The base station can transmit the data and        corresponding DCI by using the same bandwidth part, and the        terminal can obtain data scheduling information for a specific        bandwidth part from the DCI transmitted via the same bandwidth        part.    -   Cross scheduling: indicates that the DCI indicating data        scheduling and the scheduled data are transmitted via different        bandwidth parts. The base station can transmit the data and        corresponding DCI by using different bandwidth parts, and the        terminal can obtain data scheduling information for a specific        bandwidth part from the DCI transmitted via another bandwidth        part.

Self bandwidth-part scheduling or cross bandwidth-part scheduling can beconfigured by the base station for the terminal via higher layersignaling such as RRC signaling.

Embodiment 3

The third embodiment of the disclosure provides a DCI design scheme forreducing the number of blind decodings of the terminal when the controlregion of a specific bandwidth part is used to transmit not only thecorresponding DCI but also the DCI for another bandwidth part.

As described in the second embodiment, the base station may notify theterminal of whether a specific bandwidth part is self-scheduled orcross-scheduled.

For example, in FIG. 6, the base station may specify configurationinformation indicating that DCI #1 containing scheduling information forbandwidth part #1 (602) and DCI #2 containing scheduling information forbandwidth part #2 (603) are both transmitted via control region #1 (612)of bandwidth part #1 (602). Self-scheduling is performed for bandwidthpart #1 (602) and cross-scheduling is performed for bandwidth part #2(603).

Since bandwidth part #1 (602) and bandwidth part #2 (603) can be set bydifferent system parameters, the DCIs (DCI #1 and DCI #2) for individualbandwidth parts may have different sizes.

Different bandwidth parts can have bandwidths of different sizes anddifferent subcarrier spacings, and thus can have different numbers ofRBs or RBGs of different sizes. The DCI for each bandwidth part maycontain data scheduling information for the corresponding bandwidth part(frequency-domain resource allocation information (i.e., RBallocation)). For different bandwidth parts set by different parameters(bandwidth, subcarrier spacing, number of RBs, and RBG size), the numberof bits required for RB allocation may differ and thus the overall DCIsizes may differ.

Different bandwidth parts may have different subcarrier spacings anddifferent numbers of OFDM symbols per slot, and thus may have differentslot durations. The DCI for each bandwidth part may contain datascheduling information for the corresponding bandwidth part (i.e.,time-domain resource allocation information).

The time-domain resource allocation information may be represented bythe first OFDM symbol index (start point) at which data transmissionstarts, the last OFDM symbol index (end point) at which datatransmission ends, the total number of OFDM symbols used for datatransmission (data length), the slot index at which data transmission isperformed, or the total number of slots used for data transmission, or acombination thereof. For different bandwidth parts set by differentparameters affecting time-domain resource allocation, such as differentsubcarrier spacings, different numbers of OFDM symbols per slot, anddifferent slot durations, the number of bits required for time-domainresource allocation for data may differ and thus the overall DCI sizesmay differ.

Therefore, when the terminal examines control region #1 (612) to detectDCI #1 and DCI #2, since the terminal should perform blind decoding byassuming the sizes of DCI #1 and DCI #2, the number of blind decodingscan be increased.

In the third embodiment of the disclosure, the DCIs for differentbandwidth parts are set to be equal in size. The terminal does not haveto perform additional blind decoding owing to different DCI sizes. It ispossible for the terminal to decrease the number of blind decodings,effectively reducing power consumption.

Embodiment 3-1

The sizes of the DCIs for the bandwidth parts can be made equal to thelargest DCI size. Here, zero bits (bits padded with zeros) can beappended to the DCI of a small size so as to make it have the same sizeas the DCI of a relatively large size.

More specifically, and with reference to FIG. 6, when the size of DCI #1for bandwidth part #1 (602) is M bits and the size of DCI #2 forbandwidth part #2 (603) is N bits, if M is greater than N, (M−N) zerobits may be appended to DCI #2 so as to make DCI #2 have the same sizeas DCI #1.

To transmit DCI #1, the base station can directly transmit DCI #1 of Mbits to the terminal. To transmit DCI #2, the base station can generateDCI #2 of N bits, pad DCI #2 with (M−N) zero bits, and transmit DCI #2of M bits to the terminal.

When the terminal monitors control region #1 (612) for DCI #1 and DCI#2, it can perform blind decoding by assuming that the DCI size is Mbits (i.e., the size of DCI #1 with a larger size). Upon obtaining DCI#1 after blind decoding, the terminal can directly receive it as controlinformation. Upon obtaining DCI #2 after blind decoding, the terminalcan extract valid information of N bits from DCI #2 on the assumptionthat (M−N) zero bits are padded.

Embodiment 3-2

The base station can specify the size of the DCI to be monitored by theterminal in the control region. This information may be sent by the basestation to the terminal via higher layer signaling such as RRC signalingor MAC CE signaling. If the actual DCI size and the specified DCI sizeare different, the DCI size may be adjusted in different ways. Forexample, if the actual DCI size is less than the specified DCI size,zero bits can be appended to the corresponding DCI to make it have thespecified DCI size before transmission. If the actual DCI size isgreater than the specified DCI size, some bits of the corresponding DCImay be not transmitted. It is possible not to transmit some of the bitsindicating frequency-domain resource allocation (DCI shortening or DCItruncation). When M bits are used as a bitmap indicator forfrequency-domain resource allocation, and if it is necessary to shortenthe DCI by N bits according to the specified DCI size, only (M-N) bitscan be used for the field for resource allocation. DCI shortening can beperformed in various other ways.

The terminal can perform blind decoding in the configured control regionby assuming the DCI size notified from the base station.

More specifically, and with reference to FIG. 6, it is assumed that thesize of DCI #1 for bandwidth part #1 (602) is M bits, the size of DCI #2for bandwidth part #2 (603) is N bits, and the base station sets thesize of the DCI to be monitored to L bits. The values of M, N and L maybe equal to or different from each other. If L>M, (L−M) zero bits may beappended to DCI #1 to make it have a size of L bits before transmission.If L<N, one or more fields of DCI #2 may be shortened to make it have asize of L bits before transmission. The field of the DCI to be shortenedand the amount of bits to be dropped can be specified in advance or setvia higher layer signaling.

Embodiment 3-3

Specific fields of different DCIs for different bandwidth parts may bedesigned to have the same size. Among the fields in the DCI, thetime-domain resource allocation indicator and the frequency-domainresource allocation indicator may have different sizes according to theconfiguration information of the corresponding bandwidth part.

Embodiment 3-3-1

In different DCIs for different bandwidth parts, the fields for thetime-domain resource allocation information can be made to have the samesize. More specifically, the following schemes can be applied.

Scheme 1

To make the time-domain resource allocation fields of the DCIs fordifferent bandwidth parts have the same size, the sizes of thetime-domain resource allocation fields can be made equal to the largerfield size. When the size of the time-domain resource allocation fieldin DCI #1 for bandwidth part #1 is M bits and the size of thetime-domain resource allocation field in DCI #2 for bandwidth part #2 isN bits, and if M>N, the size of the time-domain resource allocationfield of DCI #2 can be assumed to be N, and (M−N) zero bits can beappended to the time-domain resource allocation field of DCI #2.

Scheme 2

To make the time-domain resource allocation fields of the DCIs fordifferent bandwidth parts have the same size, the sizes of thetime-domain resource allocation fields can be made equal to the smallerfield size. When the size of the time-domain resource allocation fieldin DCI #1 for bandwidth part #1 is M bits and the size of thetime-domain resource allocation field in DCI #2 for bandwidth part #2 isN bits, and if M>N, the size of the time-domain resource allocationfield of DCI #1 can be assumed to be M. The time-domain resourceallocation field of DCI #2 without size change can be interpreted in theconventional way.

The time-domain resource allocation field of DCI #1 whose size isreduced from M bits to N bits can be interpreted differently from theconventional one. For example, assume that the slot duration ofbandwidth part #1 is 14 OFDM symbols, then DCI #1 can indicate the startpoint of the corresponding data with 4 bits, and assume that the slotduration of bandwidth part #2 is 7 OFDM symbols, then DCI #2 canindicate the start point of the corresponding data with 3 bits. Thetime-domain resource allocation field of DCI #1 can be assumed to be 3bits, and the data start point corresponding to 14 symbols can beremapped via a 3-bit indicator. For example, the 3-bit indicator may beused to indicate the even-numbered indexes {2, 4, 6, 8, 10, 12, 14} orthe odd-numbered indexes {1, 3, 5, 7, 9, 11} among the 14 symbolindexes.

How to interpret the time-domain resource allocation as to the changedDCI field can be specified in advance through system parameters.Alternatively, the base station can redefine information on the mappingbetween the corresponding indicator and the time-domain resourceallocation and notify it to the terminal via higher layer signaling.

For different DCIs having the same size, the terminal may identify thebandwidth part associated with a particular DCI, and may interpret thesame DCI information differently. When the DCI obtained through blinddecoding is associated with bandwidth part #1, a first analysis scheme(i.e., mapping between the DCI indicator and the time-domain resourceallocation information) can be applied to the time-domain resourceallocation field of the DCI, and when the DCI obtained through blinddecoding is associated with bandwidth part #2, a second analysis scheme(i.e., mapping between the DCI indicator and the time-domain resourceallocation information) can be applied to the time-domain resourceallocation field of the DCI. How to interpret the time-domain resourceallocation as to the DCI with a changed field (i.e., configurationinformation about first and second analysis schemes) can be specified inadvance through system parameters or be notified by the base station tothe terminal via configuration information.

Embodiment 3-3-2

In different DCIs for different bandwidth parts, the fields for thefrequency-domain resource allocation information can be made to have thesame size. More specifically, the following schemes can be applied.

Scheme 1

For different bandwidth parts, if the sizes of the bandwidth parts arethe same and the subcarrier spacings are different, the DCI fields forthe frequency-domain resource allocation information can be made to havethe same size by scaling the RBG size according to the subcarrierspacing. More specifically, assume that for bandwidth part #1, thesubcarrier spacing is Δf1 and the RBG size is M, then for bandwidth part#2, the subcarrier spacing is Δf2 and the RGB size is N. IfΔf2=Δf1*2^(n), scaling may be performed according to N=M/2^(n). Forexample, assume that both bandwidth part #1 and bandwidth part #2 have abandwidth size of 10 MHz, bandwidth part #1 has a subcarrier spacing of15 kHz, and bandwidth part #2 has a subcarrier spacing of 30 kHz, then,the number of RBs for bandwidth part #1 may be twice as many as that forbandwidth part #2. When the RBG size for bandwidth part #1 is M, the RBGsize for bandwidth part #2 may be set to M/2, thereby making the numberof bits required for the frequency-domain resource allocation forbandwidth part #1 equal to the number of bits required for thefrequency-domain resource allocation for bandwidth part #2.

When performing data scheduling for each bandwidth part, the basestation can assume the RBG size given by scheme 1 described above, andcan determine frequency-domain resource allocation information of thecorresponding DCI according to the assumed RBG size. The terminal canobtain the DCI information for each bandwidth part by assuming the RBGsize given by scheme 1 described above.

Scheme 2

If different bandwidth parts have the same number of RBs, the same RBGsize can be assumed. If both bandwidth part #1 and bandwidth part #2 arecomposed of M RBs, it can be assumed that the RBG size is N forbandwidth part #1 and bandwidth part #2.

When performing data scheduling for each bandwidth part, the basestation can assume the RBG size given by scheme 2 described above, andcan determine frequency-domain resource allocation information of thecorresponding DCI according to the assumed RBG size. The terminal canobtain the DCI information for each bandwidth part by assuming the RBGsize given by scheme 2 described above.

Scheme 3

To make the time-domain resource allocation fields of the DCIs fordifferent bandwidth parts have the same size, the base station cannotify the terminal of the RBG size for each bandwidth part. This may beachieved via higher layer signaling such as RRC signaling or MAC CEsignaling. For each bandwidth part, the terminal can determine the sizeof the field for the frequency-domain resource allocation information inthe DCI according to the RBG size notified by the base station, candetermine the overall DCI size, and can obtain the corresponding DCIthrough blind decoding.

Scheme 4

To make the time-domain resource allocation fields of the DCIs fordifferent bandwidth parts have the same size, the sizes of thefrequency-domain resource allocation fields can be made equal to thelarger field size. More specifically, when the size of thefrequency-domain resource allocation field in DCI #1 for bandwidth part#1 is M bits and the size of the frequency-domain resource allocationfield in DCI #2 for bandwidth part #2 is N bits, and if M>N, the size ofthe frequency-domain resource allocation field of DCI #2 can be assumedto be N, and (M−N) zero bits can be appended to the frequency-domainresource allocation field of DCI #2.

For each bandwidth part, the base station can determine the size of thefrequency-domain resource allocation field in the DCI by using scheme 4described above. For each bandwidth part, the terminal can assume thesize of the frequency-domain resource allocation field in the DCI givenby scheme 4 described above and perform blind decoding on the DCI.

Scheme 5

To make the time-domain resource allocation fields of the DCIs fordifferent bandwidth parts have the same size, the sizes of thefrequency-domain resource allocation fields can be made equal to thesmaller field size. More specifically, when the size of thefrequency-domain resource allocation field in DCI #1 for bandwidth part#1 is M bits and the size of the frequency-domain resource allocationfield in DCI #2 for bandwidth part #2 is N bits, and if M>N, the size ofthe frequency-domain resource allocation field of DCI #1 can be assumedto be M.

The frequency-domain resource allocation field of DCI #2 without sizechange can be interpreted in the conventional way. The frequency-domainresource allocation field of DCI #1 whose size is reduced from M bits toN bits can be interpreted differently from the conventional one. How tointerpret the frequency-domain resource allocation as to the changed DCIfield can be specified in advance through system parameters.Alternatively, the base station can redefine information on the mappingbetween the corresponding indicator and the frequency-domain resourceallocation and notify it to the terminal via higher layer signaling.

For different DCIs having the same size, the terminal may identify thebandwidth part associated with a particular DCI, and may interpret thesame DCI information differently. When the DCI obtained through blinddecoding is associated with bandwidth part #1, a first analysis scheme(i.e., mapping between the DCI indicator and the frequency-domainresource allocation information) can be applied to the frequency-domainresource allocation field of the DCI, and when the DCI obtained throughblind decoding is associated with bandwidth part #2, a second analysisscheme (i.e., mapping between the DCI indicator and the frequency-domainresource allocation information) can be applied to the frequency-domainresource allocation field of the DCI. How to interpret thefrequency-domain resource allocation as to the DCI with a changed field(i.e., configuration information about first and second analysisschemes) can be specified in advance through system parameters or benotified by the base station to the terminal via configurationinformation.

Embodiment 3-3-3

In the DCIs for different bandwidth parts, it is possible to make thefields corresponding to the overall resource allocation information havethe same overall size (i.e., the sum of the sizes of the time-domainresource allocation field and the frequency-domain resource allocationfield). More specifically, for bandwidth part #1, assume that the sizeof the time-domain resource allocation field of is M1 bits and the sizeof the frequency-domain resource allocation field is N1 bits, and forbandwidth part #2, assume that the size of the time-domain resourceallocation field of is M2 bits and the size of the frequency-domainresource allocation field is N2 bits. The sizes of the above fields maybe adjusted so as to satisfy Equation (4) below.

M1+N1=M2+N2  (4)

The overall size of the fields corresponding to the overall resourceallocation information may be specified in advance, may be determinedbased on the larger field size for a specific bandwidth part, or may bedetermined based on the smaller field size for a specific bandwidthpart. The size information may be notified by the base station to theterminal via higher layer signaling such as RRC signaling or MAC CEsignaling.

For each bandwidth part, the terminal may assume the overall size of theresource allocation fields determined based on the above scheme andobtain the corresponding DCI.

Embodiment 4

In the fourth embodiment of the disclosure, an additional field isprovided in the DCI exchanged between the base station and the terminal.

The base station and the terminal can transmit and receive data by usingone or more carriers (or, component carriers). For each carrier, one ormore bandwidth parts may be configured to enable the base station andthe terminal to transmit and receive data. The base station may notifythe terminal of information on the carrier to be used for datatransmission and reception via higher layer signaling (e.g., RRCsignaling or MAC CE signaling). The base station may also notify theterminal of the configuration information about the bandwidth part ineach carrier via higher layer signaling (e.g., RRC signaling or MAC CEsignaling). The base station and the terminal can transmit and receivedata through a bandwidth part configured on the carrier.

The DCI for a specific carrier may be transmitted or received via thesame carrier (self-scheduling) or via another carrier(cross-scheduling). The base station may notify the terminal of theconfiguration for the carrier via which the DCI for a specific carrieris to be transmitted through higher layer signaling (e.g., RRC signalingor MAC CE signaling).

As described above, the base station and the terminal can transmit andreceive data through one or more carriers. The base station and theterminal can transmit and receive data through one or more bandwidthparts of each carrier. In the fourth embodiment, the DCI exchangedbetween the base station and the terminal may further include thefollowing fields.

Alternative 1

-   -   Carrier indicator: indicates the carrier to which the received        DCI corresponds and may be composed of N bits. This can be used        to notify the terminal of one of up to 2^(N) carrier indexes.    -   Bandwidth part indicator: indicates the bandwidth part to which        the received DCI corresponds and may be composed of M bits. This        can be used to notify the terminal of one of up to 2^(M)        bandwidth part indexes.

With respect to Alternative 1 described above, the value of Ncorresponding to the number of carrier indicator bits may be fixed as asystem parameter. Alternatively, the base station may determine thevalue of N as the number of bits used for the carrier indicator. Thebase station may notify the terminal of the value of N through higherlayer signaling (e.g., RRC signaling or MAC CE signaling).

With respect to Alternative 1 described above, the carrier indicated bythe carrier indicator can be specified in advance. More specifically,assume that there are C carriers and N bits that are used as the carrierindicator, then the base station can select 2^(N) carriers from amongthe C carriers and map the selected 2^(N) carriers using an indicator ofN bits. For example, assume that there are C (e.g., 8) carriers {C1, C2,C3, C4, C5, C6, C7, C8} and N (=2) bits that are used as the carrierindicator, then, the base station can select 2^(N) (=4) carriers (e.g.,{C1, C2, C4, C7}) from among the 8 carriers and map the selected fourcarriers using the carrier indicator value {00, 01, 10, 11}. Table 4illustrates this mapping.

TABLE 4 Carrier indicator Carrier index 00 C1 01 C2 10 C4 11 C7

If C<2^(N), some of the 2^(N) carrier indicator values may be reserved.For example, assume that there are C (e.g., 3) carriers {C1, C2, C3} andN (=2) bits that are used as the carrier indicator, then, the basestation may reserve one of the four carrier indicator values. Themapping can be performed as shown in Table 5.

TABLE 5 Carrier indicator Carrier index 00 C1 01 C2 10 C3 11 reserved

The base station may notify the terminal of the above information (indexof the carrier to be used and corresponding carrier indicator) throughhigher layer signaling (e.g., RRC signaling).

The terminal can receive configuration information about the carrierindicator from the base station, interpret the received carrierindicator according to the configuration information, and determine thecarrier to which the received DCI corresponds.

With respect to Alternative 1 described above, the value of Mcorresponding to the number of bandwidth part indicator bits may befixed as a system parameter. Alternatively, the base station maydetermine the value of M as the number of bits used for the bandwidthpart indicator. The base station may notify the terminal of the value ofM through higher layer signaling (e.g., RRC signaling or MAC CEsignaling).

The value of M may be set differently for each carrier. For example,when there are C carriers, B_(i){i=1, 2, . . . , C} bandwidth parts maybe configured for the i^(th) carrier. For the i^(th) carrier, the basestation may set M_(i) {i=1, 2, . . . , C} as the number of bits for thebandwidth part indicator.

The base station may also set the same number of bits for the bandwidthpart indicator for all carriers. When there are C carriers, B_(i) {i=1,2, . . . , C} bandwidth parts may be configured for the i^(th) carrier.The base station may set the value of M as the number of bits for thebandwidth part indicator for each carrier regardless of the values ofB_(i). If B_(i) is less than 2^(M), some of the 2^(M) bits may be unused(reserved).

To realize Alternative 1 described above, the bandwidth part indicatedby the bandwidth part indicator can be specified in advance. Morespecifically, assume that there are B bandwidth parts and M bits areused as the bandwidth part indicator, then, the base station can select2^(M) bandwidth parts from among the B bandwidth parts and map theselected 2^(M) bandwidth parts using an indicator of M bits. Forexample, assume that there are B (e.g., 4) bandwidth parts {BWP1, BWP2,BWP3, BWP4} and M (=1) bits that are used as the bandwidth partindicator, then, the base station can select 2^(M) (=2) bandwidth parts(e.g., {BWP1, BWP3}) from among the 4 bandwidth parts and map theselected two bandwidth parts using the bandwidth part indicator value{0, 1}. Table 6 illustrates this mapping.

TABLE 6 Bandwidth part indicator Bandwidth part index 0 BWP1 1 BWP2

If B<2^(M), some of the 2^(M) bandwidth part indicator values may beunused (reserved). For example, assume that there is B (=1) bandwidthpart {BWP1} and M (=1) bit is used as the bandwidth part indicator,then, the base station may reserve one of the two bandwidth partindicator values. Here, the mapping can be performed as shown in Table7.

TABLE 7 Bandwidth part indicator Bandwidth part index 0 BWP1 1 reserved

The base station may notify the terminal of the above information (indexof the bandwidth part for each carrier and corresponding bandwidth partindicator) through higher layer signaling (e.g., RRC signaling).

The terminal can receive configuration information about the bandwidthpart indicator from the base station, interpret the received bandwidthpart indicator according to the configuration information, and determinethe bandwidth part to which the received DCI corresponds.

The terminal can use the DCI fields described in Alternative 1 toidentify the bandwidth part of a given carrier corresponding to the DCI.The terminal can identify the carrier corresponding to the DCI based onthe carrier indicator and determine the bandwidth part of the identifiedcarrier based on the bandwidth part indicator. The terminal can transmitand receive data via the bandwidth part of the carrier corresponding tothe obtained carrier index and bandwidth part index.

Alternative 2

-   -   Carrier and bandwidth part indicator (CBPI): indicates the        bandwidth part of a specific carrier to which the received DCI        corresponds and may be composed of L bits. This can be used to        notify the terminal of one of up to 2^(L) indexes corresponding        to the combinations of the carrier index and the bandwidth part        index.

With respect to Alternative 2 described above, the value of Lcorresponding to the number of CBPI bits may be fixed as a systemparameter. Alternatively, the base station may determine the value of Las the number of bits used for the CBPI. The base station may notify theterminal of the value of L through higher layer signaling (e.g., RRCsignaling or MAC CE signaling).

With respect to Alternative 2 described above, the carrier and thebandwidth part thereof indicated by the CBPI can be specified inadvance. More specifically, assume that there are C carriers and thereare B_(i) (i=1, 2, . . . , C) bandwidth parts in each carrier, then,there can be A=Σ_(i=1) ^(C)B_(i) carrier-bandwidth part combinations.The base station may determine the value of L as the number of CBPIbits. The base station can select 2L CBP indexes (index to a bandwidthpart in a specific carrier) and map the selected CBP indexes using anindicator of L bits, and notify this configuration information to theterminal.

For example, assume that there are C (e.g., 4) carriers {C1, C2, C3,C4}, and assume that there are two bandwidth parts {BWP11, BWP12} incarrier C1, there are two bandwidth parts {BWP21, BWP22} in carrier C2,there are two bandwidth parts {BWP31, BWP32} in carrier C3, and thereare two bandwidth parts {BWP41, BWP42} in carrier C4, then, there can beA (e.g., 8) carrier-bandwidth part combinations. CBP indexes can beformed by combinations of carrier index Cx and bandwidth part indexBWPxy. Table 8 illustrates this mapping.

TABLE 8 CBP index Carrier index Bandwidth part index in each carrierCBP1 C1 BWP1 CBP2 C1 BWP2 CBP3 C2 BWP1 CBP4 C2 BWP2 CBP5 C3 BWP1 CBP6 C3BWP2 CBP7 C4 BWP1 CBP8 C4 BWP2

The base station can set L (=2) bits for the CBPI size. The base stationcan select 2^(L) (e.g., 4) CBP indexes from among the 8 CBP indexes andmap them using the CBPI. The base station may select {CBP1, CBP2, CBP5,CBP8} from among the 8 CBP indexes and map them using CBPI {00, 01, 10,11}. This can be summarized in Table 9.

TABLE 9 CBPI CBP index 00 CBP1 01 CBP2 10 CBP5 11 CBP8

If A<2^(L), some of the 2^(L) carrier indicator values may be unused(reserved). For example, assume that there are A (e.g., 3) CBP indexes{CBP1, CBP2, CBP3} and L (=2) bits that are used as the CBP indicator,then, the base station may reserve one of the four CBP indicator values.Here, the mapping can be performed as shown in Table 10.

TABLE 10 CBP indicator CBP index 00 CBP1 01 CBP2 10 CBP3 11 reserved

As described above, the base station can notify the terminal ofconfiguration information about the mapping between the CBP indicatorand the CBP index. The base station can also notify the terminal ofconfiguration information about the carrier and the bandwidth partthereof indicated by each CBP index. The base station may notify theterminal of the above information through higher layer signaling such asRRC signaling or MAC CE signaling.

The terminal can receive configuration information about the CBPindicator and the CBP index from the base station, interpret thereceived CBP indicator according to the configuration information, anddetermine the bandwidth part of the carrier to which the received DCIcorresponds. The terminal can transmit and receive data via thebandwidth part of the carrier corresponding to the obtained carrier andbandwidth part index.

Embodiment 5

The fifth embodiment of the disclosure provides a method of configuringa search space for the downlink control channel.

The search space of the 5G downlink control channel can be defined as aset of indexes of CCEs shown in FIG. 3 according to the aggregationlevel. The search space according to the fifth embodiment can be givenby Equation (5).

f(Y _(k) ,CCE index,AL,number of PDCCH candidates,carrierindex,bandwidth part index)  (5)

where f(x) represents a function with x as input.

According to Equation (5), the search space can be determined based onthe Y_(k) value, which is a specific value applicable in the k^(th) slotor subframe. The initial value Y⁻¹ may be determined by the terminal IDor a specific fixed value. The Y⁻¹ value for the terminal-specificsearch space can be determined according to the terminal ID, and the Y⁻¹value for the common search space can be determined according to aspecific value commonly known to all terminals.

According to Equation (5), the search space can be determined based onthe CCE index and the aggregation level. The CCE index to be searched bythe terminal can be calculated using a relationship (e.g., modulooperation) between the CCE index and the terminal ID (or fixed value).Also, the CCE index settable for each aggregation level can becalculated through a relationship between the CCE index and theaggregation level value. It is also possible to define a set of CCEindexes to be aggregated based on the aggregation level value.

According to Equation (5), the search space can be determined based onthe number of PDCCH candidates. The number of PDCCH candidates may bedifferent for each aggregation level value. The search space at eachaggregation level value can be defined as a set of CCEs corresponding tothe number of NR-PDCCH candidates at the aggregation level value.

According to Equation (5), the search space can be determined based onthe carrier index. For example, an offset value applicable to a set ofCCE indexes constituting a given search space can be computed inconsideration of the carrier index. The Y_(k) value corresponds to thelowest CCE index constituting the PDCCH candidates at a givenaggregation level in the k^(th) slot or subframe, and the offset valuecan be applied to the lowest CCE index in consideration of the carrierindex. This can be represented by Equation (6).

Search space=f(Y _(k)(carrier index),CCE index,AL,number of PDCCHcandidates)  (6)

where Y_(k)(carrier index) may be represented by Equation (7).

Y _(k)(carrier index)=Y _(k) +m′=Y _(k) +m+M(L)*n _(CI)  (7)

In Equation (7), the value of m may range between 0 and M^((L))−1 andM^((L)) is the number of PDCCH candidates at aggregation level L. Here,n_(CI) is a carrier index. When the terminal is configured to monitorthe carrier index, the carrier index value obtained from the DCI may beapplied. When the terminal is configured not to monitor the carrierindex, the value of n_(CI) may be set to 0.

According to Equation (5), the search space can be determined based onthe bandwidth part index. For example, an offset value applicable to aset of CCE indexes constituting a given search space can be computed inconsideration of the bandwidth part index. The Y_(k) value correspondsto the lowest CCE index constituting the PDCCH candidates at a givenaggregation level in the k^(th) slot or subframe, and the offset valuecan be applied to the lowest CCE index in consideration of the bandwidthpart index. This can be represented by Equation (8).

Search space=f(Y _(k)(bandwidth part index),CCE index,AL,number of PDCCHcandidates)  (8)

where Y_(k)(bandwidth part index) may be represented by the Equation(9).

Y _(k)(bandwidth part index)=Y _(k) +m′=Y _(k) +m+M(L)*n _(BPI)  (9)

where the value of m may range between 0 and M^((L))−1 and M^((L)) isthe number of PDCCH candidates at aggregation level L. Here, n_(BPI) isa bandwidth part index. When the terminal is configured to monitor thebandwidth part index, the bandwidth part index value obtained from theDCI may be applied. When the terminal is configured not to monitor thebandwidth part index, the value of n_(BPI) may be set to 0.

According to Equation (5), the search space can be determined inconsideration of both the carrier index and the bandwidth part index.For example, an offset value applicable to a set of CCE indexesconstituting a given search space can be computed in consideration ofthe carrier index and the bandwidth part index. This can be representedby Equation (10).

Search space=f(Y _(k)(carrier index,bandwidth part index),CCEindex,AL,number of PDCCH candidates)  (10)

where Y_(k) can be represented by Equation (11).

Y _(k)(carrier index,bandwidth part index)=Y _(k) +m′=Y _(k)+m+f(carrier index,bandwidth part index)  (11)

In Equation (11), f(Y_(k)(carrier index, bandwidth part index) is aspecific function that takes the carrier index and the bandwidth partindex as input. This can be represented by Equation (12).

f(carrier index,bandwidth part index)=M(L)*(n _(CI) +n _(BPI))  (12)

Here, n_(CI) is a carrier index and n_(BPI) is a bandwidth part index.When the terminal is configured to monitor the carrier index and thebandwidth part index, the carrier index value and the bandwidth partindex value obtained from the DCI may be applied. When the terminal isconfigured not to monitor the carrier index or the bandwidth part index,the corresponding value of n_(CI) or n_(BPI) may be set to 0.

The search space according to the fifth embodiment can be represented byEquation (13).

Search space=f(Y _(k) ,CCE index,AL,number of PDCCH candidates,CBPindex)  (13)

According to Equation (13), the search space can be determined based onthe CBP index. The CBP index (defined in the fourth embodiment of thedisclosure) is an index value mapped to a combination of the carrierindex and the bandwidth part index of the corresponding carrier. Tocompute the search space, an offset value applicable to a set of CCEindexes constituting a given search space can be computed inconsideration of the CBP index. This can be represented by Equation(14).

Search space=f(Y _(k)(CBP index),CCE index,AL,number of PDCCHcandidates)  (14)

where Y_(k)(CBP index) may be represented by Equation (15).

Y _(k)(CBP index)=Y _(k) +m′=Y _(k) +m+M(L)*n _(CBPI)  (15)

where the value of m may range between 0 and M^((L))−1 and M^((L)) isthe number of PDCCH candidates at aggregation level L. Here, n_(CBPI) isa CBP index. When the terminal is configured to monitor the CBP index,the CBP index value obtained from the DCI may be applied. When theterminal is configured not to monitor the CBP index, the value ofn_(CBPI) may be set to 0.

Next, a description is given of operations of the base station and theterminal according to the fifth embodiment of the disclosure.

The base station can determine the search space for a terminal inconsideration of the carrier index or the bandwidth part index. Totransmit or receive data for a terminal via a specific bandwidth part ofa given carrier, the base station can transmit the DCI of the terminalto the search space calculated based on the carrier index and thebandwidth part index.

For a specific bandwidth part of a given carrier, the terminal candetermine the search space to be monitored in consideration of thecarrier index and the bandwidth part index. The terminal can performblind decoding on the DCI in the calculated search space to obtain theDCI.

FIGS. 7 and 8 are diagrams of the terminal and base station,respectively. Each of the terminal and the base station includes atransmitter, a receiver, and a controller. The base station and theterminal having the above configurations should be able to performoperations for bandwidth part configuration, bandwidth part scheduling,DCI transmission, and various signaling in the 5G communication systemdescribed as embodiments.

As shown in FIG. 7, the terminal may include a processor 701, a receiver702, and a transmitter 703. The processor 701 may include one or moreprocessors. The processor 701 may be referred to as a controller.

The processor 701 may control the terminal to operate according to thedisclosure described above. For example, the processor 701 may controlthe terminal to perform different decoding operations on the downlinkcontrol channel and data channel according to the information forbandwidth part configuration, bandwidth part scheduling, and DCIreception in the embodiments.

The processor 701 may control receiving configuration information for afirst bandwidth part and a second bandwidth part from the base station,decoding, based on the size of the downlink control information (DCI)for the first bandwidth part, the DCI for the second bandwidth part inthe control region of the first bandwidth part, and identifying aninformation field included in the DCI for the second bandwidth part.

The processor 701 may identify the information field based on the sizeinformation of the DCI decoded in the second bandwidth part. If the sizeof the DCI transmitted through the second bandwidth part is greater thanthe size of the DCI for the first bandwidth part, the processor 701 maycontrol identifying the information field by determining that theinformation field included in the DCI for the second bandwidth part istruncated so as to match the DCI for the first bandwidth part.

If the size of the DCI transmitted through the second bandwidth part isless than the size of the DCI for the first bandwidth part, theprocessor 701 may control identifying the information field bydetermining that the information field included in the DCI for thesecond bandwidth part is zero padded so as to match the DCI for thefirst bandwidth part. The information field may correspond to at leastone of a frequency resource allocation field and a time resourceallocation field. The DCI for the second bandwidth part may include abandwidth part indicator indicating the second bandwidth part.

In the terminal, the receiver 702 and the transmitter 703 may becollectively referred to as a transceiver unit. The transceiver unit cantransmit and receive signals to and from the base station. The signalmay include control information and data. To this end, the transceiverunit may include an RF transmitter for up-converting the frequency of asignal to be transmitted and amplifying the signal, and an RF receiverfor low-noise amplifying a received signal and down-converting thefrequency of the received signal. The transceiver unit may receive asignal through a radio channel and output the signal to the processor701, and may transmit a signal output from the processor 701 through aradio channel.

As shown in FIG. 8, the base station may include a processor 801, areceiver 802, and a transmitter 803. The processor 801 may include oneor more processors. The processor 801 may be referred to as acontroller.

The processor 801 may control the base station to operate according tothe disclosure described above. For example, the processor 801 cancontrol the base station differently according to the operations forbandwidth part configuration, bandwidth part scheduling, and DCItransmission in the embodiments. The processor 801 can also controltransmission of various additional indicators and configurationinformation if necessary.

The processor 801 may control transmitting configuration information fora first bandwidth part and a second bandwidth part to a terminal,generating the (DCI for the second bandwidth part whose size correspondsto the size of the DCI for the first bandwidth part, and transmittingthe DCI for the second bandwidth part via the control region of thefirst bandwidth part.

If the size of the DCI to be transmitted via the second bandwidth partis greater than the size of the DCI for the first bandwidth part, theinformation field included in the DCI for the second bandwidth part maybe truncated so as to match the DCI for the first bandwidth part.

If the size of the DCI to be transmitted via the second bandwidth partis less than the size of the DCI for the first bandwidth part, theinformation field included in the DCI for the second bandwidth part maybe zero padded so as to match the DCI for the first bandwidth part. TheDCI for the second bandwidth part may include an information field, andthe information field may correspond to at least one of a frequencyresource allocation field and a time resource allocation field. The DCIfor the second bandwidth part may include a bandwidth part indicatorindicating the second bandwidth part.

In the base station, the receiver 802 and the transmitter 803 may becollectively referred to as a transceiver unit. The transceiver unit cantransmit and receive signals to and from the terminal. The signal mayinclude control information and data. To this end, the transceiver unitmay include an RF transmitter for up-converting the frequency of asignal to be transmitted and amplifying the signal, and an RF receiverfor low-noise amplifying a received signal and down-converting thefrequency of the received signal. The transceiver unit may receive asignal through a radio channel and output the signal to the processor801, and may transmit a signal output from the processor 801 through aradio channel.

In accordance with the disclosure, a terminal can operate on thebandwidth parts using the ultra-wide bandwidth operation in the 5Gcommunication system, and the 5G communication system can be operatedmore efficiently. It is possible to decrease the number of blinddecodings of the terminal and reduce power consumption of the terminal.

While the disclosure has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the scope of the disclosure. Therefore, the scopeof the disclosure should not be defined as being limited to theembodiments, but should be defined by the appended claims andequivalents thereof.

What is claimed is:
 1. A method performed by a user equipment forcommunication in a communication system supporting one or more bandwidthparts, the method comprising: identifying a first bandwidth part for acell and a second bandwidth part for the cell through a radio resourcecontrol signaling, wherein each of the first bandwidth part and thesecond bandwidth part is defined with a corresponding subcarrier spacingand frequency domain location; identifying a first control resource seton the first bandwidth part and a second control resource set on thesecond bandwidth part through the radio resource control signaling; andacquiring second downlink control information for the second bandwidthpart based on the first control resource set on the first bandwidth partbeing activated, wherein a bandwidth part indicator, a frequency domainresource assignment, and a time domain resource assignment are includedin the second downlink control information, wherein a number of bits ofbandwidth part indicator is defined based on the radio resource controlsignaling, wherein the first bandwidth part is activated by firstdownlink control information, and wherein the first downlink controlinformation and the second downlink control information are acquired ina user equipment specific control region.
 2. The method of claim 1,wherein each of the first bandwidth part and the second bandwidth partis further defined with a corresponding bandwidth.
 3. The method ofclaim 1, wherein a 0 value bandwidth part indicator corresponds to afirst bandwidth part based on an ascending order of a bandwidth partidentifier (ID).
 4. The method of claim 1, wherein a highest valuebandwidth part indicator is reserved, in case that a number of bandwidthparts is smaller than a number of values of bandwidth part indicators.5. The method of claim 1, wherein a carrier indicator is furtherincluded in the second downlink control information, and wherein thebandwidth part indicator indicates one bandwidth part among multiplebandwidth parts configured for the cell indicated by the carrierindicator.
 6. A user equipment for communication in a communicationsystem supporting one or more bandwidth parts, the user equipmentcomprising: a transceiver; and a controller coupled with the transceiverand configured to: identify a first bandwidth part for a cell and asecond bandwidth part for the cell through a radio resource controlsignaling, wherein each of the first bandwidth part and the secondbandwidth part is defined with a corresponding subcarrier spacing andfrequency domain location, identify a first control resource set on thefirst bandwidth part and a second control resource set on the secondbandwidth part through the radio resource control signaling, and acquiresecond downlink control information for the second bandwidth part basedon the first control resource set on the first bandwidth part beingactivated, wherein a bandwidth part indicator, a frequency domainresource assignment, and a time domain resource assignment are includedin the second downlink control information, wherein a number of bits ofbandwidth part indicator is defined based on the radio resource controlsignaling, wherein the first bandwidth part is activated by firstdownlink control information, and wherein the first downlink controlinformation and the second downlink control information are acquired ina user equipment specific control region.
 7. The user equipment of claim6, wherein each of the first bandwidth part and the second bandwidthpart is further defined with a corresponding bandwidth.
 8. The userequipment of claim 6, wherein a 0 value bandwidth part indicatorcorresponds to a first bandwidth part based on an ascending order of abandwidth part identifier (ID).
 9. The user equipment of claim 6,wherein a highest value of bandwidth part indicator is reserved, in casethat a number of bandwidth parts is smaller than a number of values ofbandwidth part indicators.
 10. The user equipment of claim 6, wherein acarrier indicator is further included in the second downlink controlinformation, and wherein the bandwidth part indicator indicates onebandwidth part among multiple bandwidth parts configured for the cellindicated by the carrier indicator.
 11. A method performed by a basestation for communication in a communication system supporting one ormore bandwidth parts, the method comprising: transmitting a radioresource control signaling including information for a first bandwidthpart for a cell and information for a second bandwidth part for thecell, wherein each of the first bandwidth part and the second bandwidthpart is defined with a corresponding subcarrier spacing and frequencydomain location; identifying a first control resource set on the firstbandwidth part and a second control resource set on the second bandwidthpart through the radio resource control signaling; and transmittingsecond downlink control information for the second bandwidth part basedon the first control resource set on the first bandwidth part beingactivated, wherein a bandwidth part indicator, a frequency domainresource assignment, and a time domain resource assignment are includedin the second downlink control information, wherein a number of bits ofbandwidth part indicator is defined based on the radio resource controlsignaling, wherein the first bandwidth part is activated by firstdownlink control information, and wherein the first downlink controlinformation and the second downlink control information are acquired ina user equipment specific control region.
 12. The method of claim 11,wherein each of the first bandwidth part and the second bandwidth partis further defined with a corresponding bandwidth.
 13. The method ofclaim 11, wherein a 0 value bandwidth part indicator corresponds to afirst bandwidth part based on an ascending order of a bandwidth partidentifier (ID).
 14. The method of claim 11, wherein a highest valuebandwidth part indicator is reserved, in case that a number of bandwidthparts is smaller than a number of values of bandwidth part indicators.15. The method of claim 11, wherein a carrier indicator is furtherincluded in the second downlink control information, and wherein thebandwidth part indicator indicates one bandwidth part among multiplebandwidth parts configured for the cell indicated by the carrierindicator.
 16. A base station for communication in a communicationsystem supporting one or more bandwidth parts, the base stationcomprising: a transceiver; and a controller coupled with the transceiverand configured to: transmit a radio resource control signaling includinginformation for a first bandwidth part for a cell and information for asecond bandwidth part for the cell, wherein each of the first bandwidthpart and the second bandwidth part is defined with a correspondingsubcarrier spacing and frequency domain location, identify a firstcontrol resource set on the first bandwidth part and a second controlresource set on the second bandwidth part through the radio resourcecontrol signaling, and transmit second downlink control information forthe second bandwidth part based on the first control resource set on thefirst bandwidth part being activated, wherein a bandwidth partindicator, a frequency domain resource assignment, and a time domainresource assignment are included in the second downlink controlinformation, wherein a number of bits of bandwidth part indicator isdefined based on the radio resource control signaling, wherein the firstbandwidth part is activated by first downlink control information, andwherein the first downlink control information and the second downlinkcontrol information are acquired in a user equipment specific controlregion.
 17. The base station of claim 16, wherein each of the firstbandwidth part and the second bandwidth part is further defined with acorresponding bandwidth.
 18. The base station of claim 16, wherein a 0value of bandwidth part indicator corresponds to a first bandwidth partbased on an ascending order of a bandwidth part identifier (ID).
 19. Thebase station of claim 16, wherein a highest value bandwidth partindicator is reserved, in case that a number of bandwidth parts issmaller than a number of values of bandwidth part indicators.
 20. Thebase station of claim 16, wherein a carrier indicator is furtherincluded in the second downlink control information, and wherein thebandwidth part indicator indicates one bandwidth part among multiplebandwidth parts configured for the cell indicated by the carrierindicator.